Ford, Jes and Hildebrandt, Hendrik and Van Waerbeke, Ludovic and Leauthaud, Alexie and Capak, Peter and Finoguenov, Alexis and Tanaka, Masayuki and George, Matthew R. and Rhodes, Jason (2012) Magnification by Galaxy Group Dark Matter Halos. Astrophysical Journal, 754 (2). Art. No. 143. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20120831-143730769
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We report on the detection of gravitational lensing magnification by a population of galaxy groups, at a significance level of 4.9σ. Using X-ray-selected groups in the COSMOS 1.64 deg^2 field, and high-redshift Lyman break galaxies as sources, we measure a lensing-induced angular cross-correlation between the samples. After satisfying consistency checks that demonstrate we have indeed detected a magnification signal, and are not suffering from contamination by physical overlap of samples, we proceed to implement an optimally weighted cross-correlation function to further boost the signal to noise of the measurement. Interpreting this optimally weighted measurement allows us to study properties of the lensing groups. We model the full distribution of group masses using a composite-halo approach, considering both the singular isothermal sphere and Navarro-Frenk-White profiles, and find our best-fit values to be consistent with those recovered using the weak-lensing shear technique. We argue that future weak-lensing studies will need to incorporate magnification along with shear, both to reduce residual systematics and to make full use of all available source information, in an effort to maximize scientific yield of the observations.
|Additional Information:||© 2012 IOP Publishing. Received 2011 November 15; accepted 2012 June 4; published 2012 July 18. The authors thank Fabian Schmidt and Martha Milkeraitis for useful discussions related to this work. J.F. was supported by JPL grant No. 1394704, and is now supported by NSERC and CIfAR. H.H. is supported by the Marie Curie IOF 252760 and by a CITA National Fellowship. This work was performed in part at JPL, run by Caltech under a contract for NASA. This work was supported by World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan. This work is based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and on observations made with the NASA/ESA Hubble Space Telescope. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This work is also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada–France–Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institute National des Sciences de l’Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.|
|Subject Keywords:||galaxies: photometry|
|Official Citation:||Magnification by Galaxy Group Dark Matter Halos Jes Ford et al. 2012 ApJ 754 143|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Aucoeur Ngo|
|Deposited On:||04 Sep 2012 15:33|
|Last Modified:||06 Jul 2015 17:49|
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